Focused ultrasound as a non-invasive intervention for neurological disease: a review

Focused ultrasound (FUS) is an incision-less intervention that is a Food and Drug Association (FDA) approved surgical treatment for various pathologies including uterine fibroids and bone metastases. Recent advances in magnetic resonance imaging thermometry and ability to use FUS across the intact calvarium have re-opened interest in the use of FUS in the treatment of neurological diseases. FUS currently has a European CE mark for use in movement disorders. However, it shows potential in the treatment of other neuropathologies including tumours and as a lesional tool in epilepsy. FUS may exert its therapeutic effect through thermal or mechanical fragmentation of intracranial lesions, or by enhancing delivery of pharmaceutical agents across the blood-brain barrier. In this review, we summarise the mechanisms, clinical applications and potential future of FUS for the treatment of neurological disease. We have searched for and described the recently completed and on-going clinical trials investigating FUS for the treatment of neurological disorders. We identified phase one trials investigating utility of FUS in: movement disorders (including essential tremor and Parkinson's disease), chronic pain, obsessive-compulsive disorder and cerebral tumours. Current literature also reports pre-clinical work exploring utility in epilepsy, neurodegenerative conditions (such as Alzheimer's disease) and thrombolysis. Safety and early efficacy data are now emerging, suggesting that transcalvarial FUS is a feasible and safe intervention. Further evidence is required to determine whether FUS is an effective alternative in comparison to current neurosurgical interventions. The cost of requisite hardware is currently a barrier to widespread uptake in UK neurosurgical centres.